The 6000 miles or in your case 12000km service as you said it's not a major one and it is true that most things you can do yourself, but it is there so that you can keep your warranty validated. If you don't have it serviced by an authorized dealer you would risk voiding your 2 years warranty period and if anything goes wrong then you would have a hard time getting Yamaha to replace unforeseen items that are damaged during warranty.

In additiion to what you have mentioned they should also replace: (make sure they do)

1) engine oil and oil filter
2) the paper air filter unless you have replaced this with a K&N or DNA
3) Spark plug
4) Cush driver rubber blocks

All nuts and bolts should be checked for correct torque. And a general wear and tear inspection and report should be carried out.

On the next service they will adjust your timing chain and your valve clearance, your battery will be tested and all wiring loom is also inspected.

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